Someone was asking for the "design" video / demo. Its here :
This is the Apple equivalent of the most excellent HP workstations... and (without getting too detailed) looks competitive for price.
Not for the majority of home users. But for 50% of creative professionals creating content (video, AR, VR, Audio, CAD, Animation etc etc) this is excellent.
The idea for storage is simple. Small (ish) extremely fast OS drive - similar (but faster) than the current darth vader box. Then you use TB3 or PCIe storage for projects. OR connect to a 10GBe based (shared) storage unit.
Storage very rarely wants to be part of a workstation inside a business with more than one workstation. Projects need to be transportable between rooms / workstations. Footage gets thrown around all over the place. The days of TB upon TB of internal storage is an old paradigm that doesn't fit the workstation mode - which is clearly what this machine is designed for. (And if you like the old mode, just get yourself a large TB3 connected storage unit and never move it from beside the machine!)
Does this fit everyone's use case? Surely not. But it most certainly is catering for the facility based crowd who need tonnes of processing power, modularity and upgradability. Will many composers working on their own use it? I don't think so. Maybe the top of the mac crowd. Given the new mac mini's are so capable, ditto imacs (pro and otherwise... oh - the pro's use the same xeon family so similar power cpu wise!) then these machines are designed for a purpose, and by the looks of it (I'll reserve my complete judgement till I'm able to sit in front of one) they'll be awesome.